diff -r 902822492a68 -r fe660c52c48f includes/diffengine/Engine/native.php --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/includes/diffengine/Engine/native.php Wed Jun 13 16:07:17 2007 -0400 @@ -0,0 +1,435 @@ + 2, and some optimizations) are from + * Geoffrey T. Dairiki . The original PHP version of this + * code was written by him, and is used/adapted with his permission. + * + * $Horde: framework/Text_Diff/Diff/Engine/native.php,v 1.3 2006/01/06 15:56:52 jan Exp $ + * + * @author Geoffrey T. Dairiki + * @package Text_Diff + * + * @access private + */ +class Text_Diff_Engine_native { + + function diff($from_lines, $to_lines) + { + array_walk($from_lines, array('Text_Diff', 'trimNewlines')); + array_walk($to_lines, array('Text_Diff', 'trimNewlines')); + + $n_from = count($from_lines); + $n_to = count($to_lines); + + $this->xchanged = $this->ychanged = array(); + $this->xv = $this->yv = array(); + $this->xind = $this->yind = array(); + unset($this->seq); + unset($this->in_seq); + unset($this->lcs); + + // Skip leading common lines. + for ($skip = 0; $skip < $n_from && $skip < $n_to; $skip++) { + if ($from_lines[$skip] !== $to_lines[$skip]) { + break; + } + $this->xchanged[$skip] = $this->ychanged[$skip] = false; + } + + // Skip trailing common lines. + $xi = $n_from; $yi = $n_to; + for ($endskip = 0; --$xi > $skip && --$yi > $skip; $endskip++) { + if ($from_lines[$xi] !== $to_lines[$yi]) { + break; + } + $this->xchanged[$xi] = $this->ychanged[$yi] = false; + } + + // Ignore lines which do not exist in both files. + for ($xi = $skip; $xi < $n_from - $endskip; $xi++) { + $xhash[$from_lines[$xi]] = 1; + } + for ($yi = $skip; $yi < $n_to - $endskip; $yi++) { + $line = $to_lines[$yi]; + if (($this->ychanged[$yi] = empty($xhash[$line]))) { + continue; + } + $yhash[$line] = 1; + $this->yv[] = $line; + $this->yind[] = $yi; + } + for ($xi = $skip; $xi < $n_from - $endskip; $xi++) { + $line = $from_lines[$xi]; + if (($this->xchanged[$xi] = empty($yhash[$line]))) { + continue; + } + $this->xv[] = $line; + $this->xind[] = $xi; + } + + // Find the LCS. + $this->_compareseq(0, count($this->xv), 0, count($this->yv)); + + // Merge edits when possible. + $this->_shiftBoundaries($from_lines, $this->xchanged, $this->ychanged); + $this->_shiftBoundaries($to_lines, $this->ychanged, $this->xchanged); + + // Compute the edit operations. + $edits = array(); + $xi = $yi = 0; + while ($xi < $n_from || $yi < $n_to) { + assert($yi < $n_to || $this->xchanged[$xi]); + assert($xi < $n_from || $this->ychanged[$yi]); + + // Skip matching "snake". + $copy = array(); + while ($xi < $n_from && $yi < $n_to + && !$this->xchanged[$xi] && !$this->ychanged[$yi]) { + $copy[] = $from_lines[$xi++]; + ++$yi; + } + if ($copy) { + $edits[] = &new Text_Diff_Op_copy($copy); + } + + // Find deletes & adds. + $delete = array(); + while ($xi < $n_from && $this->xchanged[$xi]) { + $delete[] = $from_lines[$xi++]; + } + + $add = array(); + while ($yi < $n_to && $this->ychanged[$yi]) { + $add[] = $to_lines[$yi++]; + } + + if ($delete && $add) { + $edits[] = &new Text_Diff_Op_change($delete, $add); + } elseif ($delete) { + $edits[] = &new Text_Diff_Op_delete($delete); + } elseif ($add) { + $edits[] = &new Text_Diff_Op_add($add); + } + } + + return $edits; + } + + /** + * Divides the Largest Common Subsequence (LCS) of the sequences (XOFF, + * XLIM) and (YOFF, YLIM) into NCHUNKS approximately equally sized + * segments. + * + * Returns (LCS, PTS). LCS is the length of the LCS. PTS is an array of + * NCHUNKS+1 (X, Y) indexes giving the diving points between sub + * sequences. The first sub-sequence is contained in (X0, X1), (Y0, Y1), + * the second in (X1, X2), (Y1, Y2) and so on. Note that (X0, Y0) == + * (XOFF, YOFF) and (X[NCHUNKS], Y[NCHUNKS]) == (XLIM, YLIM). + * + * This function assumes that the first lines of the specified portions of + * the two files do not match, and likewise that the last lines do not + * match. The caller must trim matching lines from the beginning and end + * of the portions it is going to specify. + */ + function _diag ($xoff, $xlim, $yoff, $ylim, $nchunks) + { + $flip = false; + + if ($xlim - $xoff > $ylim - $yoff) { + /* Things seems faster (I'm not sure I understand why) when the + * shortest sequence is in X. */ + $flip = true; + list ($xoff, $xlim, $yoff, $ylim) + = array($yoff, $ylim, $xoff, $xlim); + } + + if ($flip) { + for ($i = $ylim - 1; $i >= $yoff; $i--) { + $ymatches[$this->xv[$i]][] = $i; + } + } else { + for ($i = $ylim - 1; $i >= $yoff; $i--) { + $ymatches[$this->yv[$i]][] = $i; + } + } + + $this->lcs = 0; + $this->seq[0]= $yoff - 1; + $this->in_seq = array(); + $ymids[0] = array(); + + $numer = $xlim - $xoff + $nchunks - 1; + $x = $xoff; + for ($chunk = 0; $chunk < $nchunks; $chunk++) { + if ($chunk > 0) { + for ($i = 0; $i <= $this->lcs; $i++) { + $ymids[$i][$chunk - 1] = $this->seq[$i]; + } + } + + $x1 = $xoff + (int)(($numer + ($xlim-$xoff)*$chunk) / $nchunks); + for (; $x < $x1; $x++) { + $line = $flip ? $this->yv[$x] : $this->xv[$x]; + if (empty($ymatches[$line])) { + continue; + } + $matches = $ymatches[$line]; + foreach ($matches as $y) { + if (empty($this->in_seq[$y])) { + $k = $this->_lcsPos($y); + assert($k > 0); + $ymids[$k] = $ymids[$k - 1]; + break; + } + } + + while (list($junk, $y) = each($matches)) { + if ($y > $this->seq[$k - 1]) { + assert($y < $this->seq[$k]); + /* Optimization: this is a common case: next match is + * just replacing previous match. */ + $this->in_seq[$this->seq[$k]] = false; + $this->seq[$k] = $y; + $this->in_seq[$y] = 1; + } elseif (empty($this->in_seq[$y])) { + $k = $this->_lcsPos($y); + assert($k > 0); + $ymids[$k] = $ymids[$k - 1]; + } + } + } + } + + $seps[] = $flip ? array($yoff, $xoff) : array($xoff, $yoff); + $ymid = $ymids[$this->lcs]; + for ($n = 0; $n < $nchunks - 1; $n++) { + $x1 = $xoff + (int)(($numer + ($xlim - $xoff) * $n) / $nchunks); + $y1 = $ymid[$n] + 1; + $seps[] = $flip ? array($y1, $x1) : array($x1, $y1); + } + $seps[] = $flip ? array($ylim, $xlim) : array($xlim, $ylim); + + return array($this->lcs, $seps); + } + + function _lcsPos($ypos) + { + $end = $this->lcs; + if ($end == 0 || $ypos > $this->seq[$end]) { + $this->seq[++$this->lcs] = $ypos; + $this->in_seq[$ypos] = 1; + return $this->lcs; + } + + $beg = 1; + while ($beg < $end) { + $mid = (int)(($beg + $end) / 2); + if ($ypos > $this->seq[$mid]) { + $beg = $mid + 1; + } else { + $end = $mid; + } + } + + assert($ypos != $this->seq[$end]); + + $this->in_seq[$this->seq[$end]] = false; + $this->seq[$end] = $ypos; + $this->in_seq[$ypos] = 1; + return $end; + } + + /** + * Finds LCS of two sequences. + * + * The results are recorded in the vectors $this->{x,y}changed[], by + * storing a 1 in the element for each line that is an insertion or + * deletion (ie. is not in the LCS). + * + * The subsequence of file 0 is (XOFF, XLIM) and likewise for file 1. + * + * Note that XLIM, YLIM are exclusive bounds. All line numbers are + * origin-0 and discarded lines are not counted. + */ + function _compareseq ($xoff, $xlim, $yoff, $ylim) + { + /* Slide down the bottom initial diagonal. */ + while ($xoff < $xlim && $yoff < $ylim + && $this->xv[$xoff] == $this->yv[$yoff]) { + ++$xoff; + ++$yoff; + } + + /* Slide up the top initial diagonal. */ + while ($xlim > $xoff && $ylim > $yoff + && $this->xv[$xlim - 1] == $this->yv[$ylim - 1]) { + --$xlim; + --$ylim; + } + + if ($xoff == $xlim || $yoff == $ylim) { + $lcs = 0; + } else { + /* This is ad hoc but seems to work well. $nchunks = + * sqrt(min($xlim - $xoff, $ylim - $yoff) / 2.5); $nchunks = + * max(2,min(8,(int)$nchunks)); */ + $nchunks = min(7, $xlim - $xoff, $ylim - $yoff) + 1; + list($lcs, $seps) + = $this->_diag($xoff, $xlim, $yoff, $ylim, $nchunks); + } + + if ($lcs == 0) { + /* X and Y sequences have no common subsequence: mark all + * changed. */ + while ($yoff < $ylim) { + $this->ychanged[$this->yind[$yoff++]] = 1; + } + while ($xoff < $xlim) { + $this->xchanged[$this->xind[$xoff++]] = 1; + } + } else { + /* Use the partitions to split this problem into subproblems. */ + reset($seps); + $pt1 = $seps[0]; + while ($pt2 = next($seps)) { + $this->_compareseq ($pt1[0], $pt2[0], $pt1[1], $pt2[1]); + $pt1 = $pt2; + } + } + } + + /** + * Adjusts inserts/deletes of identical lines to join changes as much as + * possible. + * + * We do something when a run of changed lines include a line at one end + * and has an excluded, identical line at the other. We are free to + * choose which identical line is included. `compareseq' usually chooses + * the one at the beginning, but usually it is cleaner to consider the + * following identical line to be the "change". + * + * This is extracted verbatim from analyze.c (GNU diffutils-2.7). + */ + function _shiftBoundaries($lines, &$changed, $other_changed) + { + $i = 0; + $j = 0; + + assert('count($lines) == count($changed)'); + $len = count($lines); + $other_len = count($other_changed); + + while (1) { + /* Scan forward to find the beginning of another run of + * changes. Also keep track of the corresponding point in the + * other file. + * + * Throughout this code, $i and $j are adjusted together so that + * the first $i elements of $changed and the first $j elements of + * $other_changed both contain the same number of zeros (unchanged + * lines). + * + * Furthermore, $j is always kept so that $j == $other_len or + * $other_changed[$j] == false. */ + while ($j < $other_len && $other_changed[$j]) { + $j++; + } + + while ($i < $len && ! $changed[$i]) { + assert('$j < $other_len && ! $other_changed[$j]'); + $i++; $j++; + while ($j < $other_len && $other_changed[$j]) { + $j++; + } + } + + if ($i == $len) { + break; + } + + $start = $i; + + /* Find the end of this run of changes. */ + while (++$i < $len && $changed[$i]) { + continue; + } + + do { + /* Record the length of this run of changes, so that we can + * later determine whether the run has grown. */ + $runlength = $i - $start; + + /* Move the changed region back, so long as the previous + * unchanged line matches the last changed one. This merges + * with previous changed regions. */ + while ($start > 0 && $lines[$start - 1] == $lines[$i - 1]) { + $changed[--$start] = 1; + $changed[--$i] = false; + while ($start > 0 && $changed[$start - 1]) { + $start--; + } + assert('$j > 0'); + while ($other_changed[--$j]) { + continue; + } + assert('$j >= 0 && !$other_changed[$j]'); + } + + /* Set CORRESPONDING to the end of the changed run, at the + * last point where it corresponds to a changed run in the + * other file. CORRESPONDING == LEN means no such point has + * been found. */ + $corresponding = $j < $other_len ? $i : $len; + + /* Move the changed region forward, so long as the first + * changed line matches the following unchanged one. This + * merges with following changed regions. Do this second, so + * that if there are no merges, the changed region is moved + * forward as far as possible. */ + while ($i < $len && $lines[$start] == $lines[$i]) { + $changed[$start++] = false; + $changed[$i++] = 1; + while ($i < $len && $changed[$i]) { + $i++; + } + + assert('$j < $other_len && ! $other_changed[$j]'); + $j++; + if ($j < $other_len && $other_changed[$j]) { + $corresponding = $i; + while ($j < $other_len && $other_changed[$j]) { + $j++; + } + } + } + } while ($runlength != $i - $start); + + /* If possible, move the fully-merged run of changes back to a + * corresponding run in the other file. */ + while ($corresponding < $i) { + $changed[--$start] = 1; + $changed[--$i] = 0; + assert('$j > 0'); + while ($other_changed[--$j]) { + continue; + } + assert('$j >= 0 && !$other_changed[$j]'); + } + } + } + +}